1.
Predjama Castle, Slovenia

Getty

Built within a cave in the middle of a towering cliff, Predjama, which dates back to 1274, is imposing by most standards. Add in local legend and you’ll be hard pressed not to get spooked: Once the residence of knight Erazem Lueger, Predjama has hidden passageways and was reputedly a site of torture and treachery. Lueger was betrayed by his servants and killed in the castle, and is said to still haunt it.

2.
Castle Fraser, Scotland

Getty

Built between 1575 and 1636 in east Scotland, Castle Fraser is famous for its elaborate architecture, beautiful farmland, and gardens—and a somewhat horrifying urban myth. According to legend, a young princess once staying at the castle was brutally murdered in her sleep. Her body was dragged down the stone stairs, leaving a trail of blood behind. As hard as they tried, the occupants could not scrub out the blood stains from the stairs, so decided to cover the staircase in wood paneling, which remains to this day. Some say the ghost of the princess still roams the halls of the castle at night.

3.
Burg Eltz, Germany

Getty

Burg Eltz dates back to 1157, and lore surrounding the castle nearly as long. Of the few rooms in the castle open to tourists, supposedly one of the most haunted is the bedroom of the once Countess Agnes. Her bed, breastplate, and battle axe remain in the room, and legend has it that she died defending the castle from an "undesirable" suitor and therefore still haunts the castle today.

4.
Chillingham Castle, England

Getty

Regarded as Britain’s most haunted castle, the aptly named Chillingham Castle has a horrific history of prisoner-ridden dungeons and well-used torture chambers. Its roll call of resident spooks include the whimpering “blue boy,” the pantry’s frail “white lady,” and the perpetually lonesome Lady Mary Berkeley. Sign up for a castle-run ghost tour, or spend the night in a self-catering apartment—if you dare. —Elissa Garay

5.
Houska Castle, Czech Republic

Alamy

Located about an hour north of Prague, Houska Castle has no fortifications, no kitchen, and had no occupants when it was built. It does, however, have something within its walls that no other castle in the world has—a large hole in the ground that many consider to be the literal gateway to hell. Houska was strategically built over the hole (which is fabled to be bottomless) to seal up the gateway and keep demonic creatures from entering our world. The demons are said to be trapped in the walls of the lower level.

Here's where the story gets really creepy: Before sealing off the gateway, nearby prisoners were granted pardons if they would agree to be lowered into the hole by a rope and report back what they saw. Legend has it that when the first prisoner was lowered, he started screaming after a few seconds. When he was raised back up, he appeared to have aged 30 years—his hair had turned white, and his face was covered in wrinkles.